The influence of trace elements such as copper upon the metabolism of plants, in particular that of trees, has long been recognized but is by no means fully understood. It is well known that certain of these trace elements are essential for the normal growth of plants. A U.S. Pat. to Laing, No. 3,074,207, which is directed to a nail device comprising a coating of certain trace element salts including copper, is of special interest. The patent contains a broad summary of the then known literature on the influence of trace metal salts. It should be noted that Laing is concerned with the maintenance of normal growth in trees. An Italian Patent No. 422,275 to Biamino discusses the therapeutic effect of a bi-metallic penetrating object such as a nail upon vegetables, this bi-metallic nail always having copper as one of the components. While Biamino speaks of the desirability of the presence of copper, he does not apply his device to trees, neither does he allege any utility other than a prophylactic effect. U.S. Pat. No. 831,678 to Osborne speaks of the strengthening of the growth of trees by driving a combination of wires of different composition, copper and iron being illustrated, into the trunk of a tree and constructing the ends of the wires in such a manner that they would conduct atmospheric electricity into the body of the tree. Osborne does not mention any particular timing for the insertion of the wires. Neither does she appear to recognize any effect upon the flowering of the tree as a result of this treatment. A similar but more controlled electrical treatment system is disclosed by Keller in U.S. Pat. No. 3,120,722. It should be noted that where a tree grows in a high fixed nitrogen area, foliage growth is encouraged while in a high potassium or high phosphorus location flowering is encouraged.